doc: commit: link to git-status(1) on all format options

`--branch` and `--long` refer to git-status(1) options but they don’t tell us
what `short-format` and `long-format` are, respectively. And `--null`
mentions “status” but does not link to the command.

Refer to git-config(1) on `--branch` like `--short` does.

`long-format` is the git-status(1) output. So we can just say that
directly.

Replace “status” with a `linkgit` on `--null`.

Signed-off-by: Kristoffer Haugsbakk <code@khaugsbakk.name>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-commit.adoc

diff --git a/Documentation/git-commit.adoc b/Documentation/git-commit.adoc
index 54c207a..8329c10 100644
--- a/Documentation/git-commit.adoc
+++ b/Documentation/git-commit.adoc
@@ -146,7 +146,8 @@
 	linkgit:git-status[1] for details. Implies `--dry-run`.
 
 `--branch`::
-	Show the branch and tracking info even in short-format.
+	Show the branch and tracking info even in short-format. See
+	linkgit:git-status[1] for details.
 
 `--porcelain`::
 	When doing a dry-run, give the output in a porcelain-ready
@@ -154,12 +155,13 @@
 	`--dry-run`.
 
 `--long`::
-	When doing a dry-run, give the output in the long-format.
-	Implies `--dry-run`.
+	When doing a dry-run, give the output in the long-format. This
+	is the default output of linkgit:git-status[1]. Implies
+	`--dry-run`.
 
 `-z`::
 `--null`::
-	When showing `short` or `porcelain` status output, print the
+	When showing `short` or `porcelain` linkgit:git-status[1] output, print the
 	filename verbatim and terminate the entries with _NUL_, instead of _LF_.
 	If no format is given, implies the `--porcelain` output format.
 	Without the `-z` option, filenames with "unusual" characters are